Roe v. Wade's lab test Roe v. Wade is put to a laboratory test

James S. Trefil AND Harold J. Morowitz

THE abortion debate has become a ritual, with both sides reduced to mouthing the same platitudes over and over again.

On one side of police barricades, angry people wave pictures of fetuses. On the other side, an equally angry group waves pictures of coat hangers.

The media round up the usual suspects, getting a sound bite from the National Abortion Rights Action League spokesman, then another from Operation Rescue.

Though few people have noticed, some astonishing scientific findings have been made in the 20 years since Roe vs. Wade that should shed new light on the issue and reinforce the reasoning behind the Supreme Court's decision.

Here's a sampling of the new information:

* Conception. There is probably no question more frustrating to a scientist than, "Does life begin at conception?"

It's like asking an engineer if a building begins when the blueprint is made. The only correct answer -- "yes and no" -- is profoundly unsatisfying.

A frequent argument against abortion is that a new DNA "blueprint" comes into existence at conception, creating the possibility of a new life.

But this argument, which owes its existence to advances in molecular biology, is threatened by advances in that field, particularly by studies of parthenogenesis -- birth without conception.

Scientists have known for a long time that unfertilized eggs of frogs, reptiles and birds can be stimulated so they divide and the two resulting cells can come together to start the development that creates an adult.

For these animals, the unfertilized egg is potential life as is the ZTC fertilized one. But this process has never really worked in the same way for mammals.

Over the last few years, however, scientists have come to understand that this is because the DNA of the mother alone is not capable of generating a full placenta, but needs to be supplemented by the DNA programmed in the father's sperm.

So mammals, up to now at least, have always required both a mother and a father.

But now that we understand why, it won't be long before we

have the technical ability to manipulate DNA so that female mammals will be capable of virgin birth.

When we reach that point, the unfertilized human egg (now routinely discarded during menstruation) will become "potential life" in the same sense that the product of conception is.

What happens to the "possible life" argument then? Are we obligated to provide every unfertilized egg with a chance to develop? Do we outlaw menstruation?

* Brain function. It is generally accepted that what distinguishes us from other animals -- what makes us human -- is the highly developed outer layers of the human brain: the "gray matter," or cerebral cortex.

The cortex is the seat of the emotions, sensations and other characteristics we consider human. So it can be argued that when a fetus acquires a functioning cortex, it has acquired humanness.

Recent work on monkeys and humans provides clues as to when the cortex develops. These studies show that while from early in pregnancy, nerve cells migrate to the area that will become the brain, they don't immediately make connections with one another.

Just as a pile of microchips isn't a computer, a collection of unconnected cells isn't a brain. It is only around the 25th week (the start of the third trimester) that the connections start to be made and the cortex starts to function.

Before that, the fetus is a human in the strict biological sense, but has not acquired the characteristics that distinguish humans from other animals.

* Survivability. A central issue in the legal arguments about abortion is at what point the fetus could survive if removed from the uterus.

The Roe vs. Wade decision to allow abortion only before the start of the third trimester was based on the reckoning that after that the fetus could survive outside the womb.

At the time, most scientists felt that medical science would steadily push this limit back to earlier periods in pregnancy. One of the most surprising "events" in developmental biology in the last 20 years is that this limit has not changed at all.

A 25-week-old fetus now has about a 50 percent chance of surviving outside the womb. But a 23-week-old fetus still has virtually none and neonatologists have no expectation that this situation will change any time soon.

The start of the third trimester marks both the point at which the fetus has a reasonable chance to survive and at which it starts to acquire a functioning cerebral cortex.

For several reasons they never could have guessed, the justices got it right in Roe vs. Wade after all.

James S. Trefil and Harold J. Morowitz are authors of "The Facts of Life: Science and the Abortion Controversy."